A NEW FURANOSESTERTERPENE FROM THE SOUTH-AFRICAN NUDIBRANCH HYPSELODORIS-CAPENSIS AND A DICTYOCERATIDA SPONGE

The known cytotoxic, linear beta-substituted sesterterpenes (18R)-vari abilin (1) and 22-deoxyvariabilin (4) and a new variant, 22-deoxy-23-h ydroxymethylvariabilin (5), were isolated from the endemic South Afric an nudibranch Hypselodoris capensis together with the known ichthyotox ic sesquiterpenes nakafuran-8 (2) and -9 (3). One of H. capensis' diet ary sponges, a Fasciospongia sp, collected simultaneously with the nud ibranchs, yielded sesterterpenes 1, 4, and 5 and the ubiquitous prenyl ated furan derivative, furospinosulin-1 (7).